The present disclosure relates to a method for manufacturing a solar panel.
Japanese Laid-Open Patent Publication No. 2010-149506 discloses a conventional method for manufacturing a solar panel (hereinafter simply referred to as the conventional manufacturing method). The conventional manufacturing method includes a preparation step, a mounting step, and a laminating step. The conventional manufacturing method involves the use of a laminating device that includes a diaphragm, a laminating jig, and a heater. The diaphragm is opposed to the laminating jig. The heater is capable of heating the laminating jig.
In the conventional manufacturing method, the preparation step is performed first. The preparation step involves the preparation of a laminated body that includes a protection cover, a back cover, photovoltaic battery cells, and an encapsulant. The protection cover is light-transmissive from its front surface to its rear surface and is curved in a convex manner from the rear surface toward the front surface. The back cover is a flat plate. The above-described document does not explicitly describe the materials of the protection cover and the back cover. The protection cover is generally made of glass but may recently be made of plastic from the perspective of weight reduction. The back cover is generally made of plastic.
The photovoltaic battery cells are arranged in a matrix manner. The encapsulant includes two encapsulant sheets, namely, a first encapsulant sheet and a second encapsulant sheet. The laminated body is formed by laminating the protection cover, the first encapsulant sheet, the photovoltaic battery cells, the second encapsulant sheet, and the back cover in this order.
Then, the mounting step is performed. In the mounting step, the laminated body is mounted on the laminating jig with the protection cover, more specifically, the front surface of the protection cover abutting the laminating jig. The laminating jig is curved so that its middle part is recessed in conformance with the shape of the protection cover. Thus, mounting the laminated body on the laminating jig causes the front surface of the protection cover to abut the laminating jig.
Subsequently, the laminating step is performed. In the laminating step, the laminating jig heated by the heater is pressed on the protection cover to heat the laminated body. This softens the back cover and the two encapsulant sheets. In this state, the laminated body is held between the diaphragm and the laminating jig to compression-bond the laminated body. This causes the back cover to be pressed by the diaphragm and curved in a convex manner toward the protection cover to have a product shape. In addition, the two softened encapsulant sheets are integrated so that the encapsulant holds the photovoltaic battery cells in an encapsulated state between the protection cover and the back cover. This integrates the protection cover, the back cover, the photovoltaic battery cells, and the encapsulant. In this manner, the solar panel is manufactured. In the solar panel, the front surface of the protection cover serves as a design surface.
In the above-described conventional manufacturing method, curving the back cover from a flat shape into the product shape in a preferred manner requires the back cover to be heated to a glass transition temperature and sufficiently softened. However, in the conventional manufacturing method, since the front surface of the protection cover abuts the laminating jig, the back cover is located at the farthest position from the laminating jig in the laminated body. Accordingly, heating the back cover to the glass transition temperature would require the laminating jig to be correspondingly heated to a high temperature and pressed on the protection cover. If the protection cover is made of plastic, heating the back cover to a high temperature by the laminating jig causes the protection cover to reach the glass transition temperature. This unnecessarily softens the protection cover and easily roughens its front surface, thereby deteriorating the aesthetic appeal of the manufactured solar panel.
Heating the laminated body to prevent the plastic protection cover from reaching the glass transition temperature prevents the back cover from reaching the glass transition temperature and being sufficiently softened. Thus, the back cover is not curved in a preferred manner. This causes, for example, the back cover to be creased and air to be trapped between the back cover and the encapsulant. Accordingly, the conventional manufacturing method makes it difficult to manufacture a high-quality solar panel including a plastic protection cover and a plastic back cover.